The decay of wood and cellulose by fungi causes significant economic loss. Until recently, the most widely used wood preservative has been chromated copper arsenate (CCA). However, issues have been raised concerning the environmental impact of arsenic and chromium used in CCA-treated lumber. To address these issues, arsenic- and chromium-free wood preservatives are sought.
Wood preservation formulations containing copper-chelating molecules are known in the art. One such preservative system is based on a copper complex, Cu-HDO, which contains a bidentate ligand, N-nitrosylated cyclohexyl-hydroxylamine (DE 3,835,370). Another alternative wood preservative is ACQ, an Ammoniacal Copper Quaternary compound (U.S. Pat. No. 4,929,454).
Many metal-chelating functionalities are known, causing a central metal ion to be attached by coordination links to two or more nonmetal atoms (ligands) in the same molecule. Heterocyclic rings are formed with the central (metal) atom as part of each ring. Polyhydroxamic acids are known and have been shown to complex with copper. Amidoxime or hydroxamic acids of cyanoethylated cellulose are known as complexation agents for metal ions, including copper (Altas H. Basta, International Journal of Polymeric Materials, 42, 1-26 (1998)).
In spite of these and other attempts to develop CCA alternatives, there remains a need for improved wood preservatives.